1. Field of the Invention
The present invention relates to a connector for optical fiber in an optical communication equipment such as an optical data link, in particular to an improvement of a ferrule which is one member of a plug side of the connector.
2. Description of the Prior Art
FIG. 1 is a schematic structural view of a connector for optical fiber, in which reference numeral 10 designates a plug and 13 designates a module provided with a receptacle 14. The module 13 comprises the receptacle 14, elements 15, 16 arranged within said receptacle 14 and an electronic circuit connected with these components. Optical fiber cords 1, 1 are connected either separately or in a bundle to other apparatus and connected to the plug 10 at the ends thereof. That is to say, a pointed end portion of each optical fiber cord 1 is bared of its cover and fitted into each metallic cylindrical ferrule 4 serving to protect the rest of the bared portion of the cord 1. The base ends of the optical fiber cords 1, 1 or ferrules 4, 4 are held in a housing 11 of the plug 10. The housing 11 is provided with cylindrical projections 11a, 11a at pointed end portion thereof, the ferrules 4, 4 somewhat projecting from the projections 11a, 11a.
The projections 11a, 11a are inserted into a housing 17 of the receptacle 14, an opto-electrical transfer element 15 and an electro-optical transfer element 16 within the module 13 facing to the optical fibers 1a, 1a inserted into the ferrules 4, 4. The module 13 contains said elements 15, 16, which are connected in parallel with each other, therein, these elements 15, 16 being connected to a receiving side circuit and a transmitting side circuit (not shown), respectively.
FIG. 2 is a half sectional view showing the construction of the conventional ferrule 4. The ferrule 4 has a smaller outside diameter within the projection 11a of the housing 11 and a portion of the pointed end side all along from said projection 11a. Washers 12, 12 to be a spring seat of a coiled spring 22 are mounted on a larger diameter portion in the housing 11 fixedly at a pointed end side thereof and slidably at a base end side thereof. The coiled spring 22 is interposed between both washers so as to apply a pressing force to the ferrule 4 when the projection 11a of the plug 10 is inserted into the housing 17 of the receptacle 14, whereby suitably maintaining a positional relation between the ferrule 4 and the module 13. The bared portion of the optical fiber cord 1 is further bared of its jacket 1b to expose the optical fiber 1a, the exposed optical fiber 1a being inserted into the ferrule 4 as far as a pointed end of the ferrule 4.
The optical fiber 1a is inserted into an optical fiber-inserting-bore 4c of the ferrule 4, which is under the condition that its inside is filled with a resin 19, as shown in FIG. 2, in the terminal treatment thereof and its pointed end somewhat projects out of the ferrule 4. After the resin 19 is set, an end face of the optical fiber 1a is polished so that the ferrule 4 and the optical fiber 1a are on the same level.
However, the above described connector for optical fiber has a problem in that the setting and polishing of the resin 19 take a time in the terminal treatment of the optical fiber 1a, the workability being inferior due to the use of a resin, and the setting state of the resin 19 being unstable according to the environmental conditions such as temperature and humidity.